Differentiate between Char and Varchar Data Type

CHAR and VARCHAR are two data types in SQL and used to store character strings.CHAR is a fixed-length character string data type, which means that it reserves a specific amount of memory for each value, VARCHAR, on the other hand, is a variable-length character string data type, which only reserves as much memory as the string requires.

Char Datatype

The CHAR datatype in SQL is used to store character strings of a fixed length. It allows you to store character data of a specific length, for example, a CHAR(10) column can store strings of exactly 10 characters. If a string is shorter than the specified length, spaces are added to make up the difference, so the data stored in a CHAR column will always have a fixed length.

The CHAR datatype is useful in cases where you want to enforce a specific length for a column, such as when you want to store a code, a product identifier, or a phone number. Since CHAR data is stored in a fixed-length format, it can be faster to retrieve than variable-length data.

However, it is important to note that using CHAR columns can result in wasted space if the data stored is shorter than the specified length.

Example of Char Datatype

In this example we create a table with attributes Name and Gender with Varchar and Char data types respectively

CREATE TABLE Student(Name VARCHAR(30), Gender CHAR(6));
INSERT into Student VALUES('Mohit', 'Male');
INSERT into Student VALUES('Anjali', 'Female');
SELECT LENGTH(Gender) FROM Student;

Output

Length(Gender)
6
6

Explanation of the above example
If we observe on output screen the length of Gender is fixed which is 6, this shows
That length of Char datatype string are fix, here male string has 4 characters but still it’s showing 6 because remaining spaces are added

Varchar Datatype

VARCHAR is a variable-length character string data type in SQL used to store alphanumeric values of limited length. It is used to store text data and its length can be specified in the definition, for example, VARCHAR(50) would indicate that the text string stored can be at most 50 characters long. The main advantage of using VARCHAR over a fixed-length data type such as CHAR is that it uses only the storage necessary for the data it holds, which can result in more efficient use of storage.

Example of Varchar Datatype

Here also taken the same table just to check the length of gender attribute.

CREATE TABLE Student(Name VARCHAR(20), Gender CHAR(6));
INSERT into Student VALUES('Mohit', 'Male');
INSERT into Student VALUES('Anjali', 'Female');
SELECT LENGTH(Name) FROM Student;

Output

Length(Name)
5
6

Explanation of the above code
Here we have a variable result which is showing the actual length of string, So this is the main difference between char and varchar data type.

Differentiate between Char and Varchar Datatypes

Now we differentiate between char and varchar data types:

Varchar	Char
Varchar fields do not have a fixed length	Char fields have a fixed length specified when creating the field
Flexibility: varchar is more flexible than char	Char is less flexible than Varchar
Varchar uses less space	Char uses a fixed amount of space regardless of the length of the string
Sorting is slow in Varchar as compare to char	Char fields are faster to sort
Varchar is more commonly used in modern databases and programming languages.	Char fields are more compatible with older database systems and are easier to work with in some programming languages

Use of Char Datatype

As we know CHAR data type in SQL is a fixed-length character string data type used to store alphanumeric values of a specified length. a

• Storing values with a fixed length, such as postal codes, product codes, etc.
• Storing values with a known length that will not change, such as gender or marital status.
• Padding values to a fixed length to improve the appearance of reports.

It’s important to note that using the CHAR data type will always result in a fixed-length string and any unused space will be filled with padding characters. This can result in wasted storage space, so it’s important to choose the appropriate data type based on the specific requirements of your application.

Use of Varchar Datatype

As we know VARCHAR data type is used to store variable-length alphanumeric values, allowing for storage of only the amount of data needed to represent the value.

• Character data storage: VARCHAR is used to store character data such as names, addresses, and other textual information.
• Dynamic data storage: VARCHAR is suitable for storing dynamic data that may vary in length, such as product descriptions, comments, and other user-generated content.
• Reduced storage space: VARCHAR uses less storage space than CHAR when storing values that are shorter than the maximum length specified, as it does not require padding.
• Improved data retrieval performance: VARCHAR can lead to improved performance when retrieving data, as it does not waste storage space and reduces the amount of data that needs to be read from disk. However, it’s important to consider the trade-off between storage space and the increased processing time required to manage variable-length data

Char vs Varchar Mysql
CHAR is a fixed-length data type and is used to store strings of a fixed length. If a string is shorter than the specified length, spaces are added to make up the difference. For example, if you define a column as CHAR(10), it will store strings of exactly 10 characters, including any trailing spaces.

VARCHAR, on the other hand, is a variable-length data type and is used to store strings of varying lengths. The length of the string is stored along with the string itself, so only the exact amount of space needed is used. For example, if you define a column as VARCHAR(10), it will store strings of up to 10 characters.

In general, it is recommended to use VARCHAR instead of CHAR as it is more flexible and efficient in terms of storage.

Conclusion
In SQL, CHAR, and VARCHAR are both used to store character strings, but there is a difference in the way they store and retrieve data.

Frequently Asked Questions(FAQ):

Q1: What is the difference between CHAR and VARCHAR data types?
CHAR is a fixed-length character string data type, used to store alphanumeric values of a specified length. VARCHAR is a variable-length character string data type, used to store alphanumeric values of limited length. In CHAR, values are always stored with the same length, even if the actual value stored is shorter, whereas VARCHAR uses only the storage necessary for the data it holds.

Q2 : When should I use CHAR and when should I use VARCHAR?
CHAR is suitable for storing values with a fixed length, such as postal codes, product codes, and other values that will not change. VARCHAR is suitable for storing dynamic data that may vary in length, such as product descriptions, comments, and other user-generated content.

Q3: Does CHAR use more storage space than VARCHAR?
CHAR uses more storage space than VARCHAR when storing values that are shorter than the maximum length specified, as it requires padding. VARCHAR uses only the storage necessary for the data it holds, making it a more efficient option when storing variable-length data.

Q4: Does the length specified in the CHAR data type definition affect performance?
The length specified in the CHAR data type definition does not directly affect performance, but larger lengths may lead to a greater waste of storage space, which can have an indirect impact on performance.

Q5: Can I change the length of a CHAR or VARCHAR column after it has been created?
It is generally not possible to change the length of a CHAR or VARCHAR column after it has been created. To change the length, you would typically need to create a new column with the desired length, copy the data from the old column to the new column, and then drop the old column.